11,280 research outputs found

    Capitalizing China

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    On the striated regularity for the 2D anisotropic Boussinesq system

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    In this paper, we investigate the global existence and uniqueness of strong solutions to 2D Boussinesq system with anisotropic thermal diffusion or anisotropic viscosity and with striated initial data. Using the key idea of Chemin to solve 2-D vortex patch of ideal fluid, namely the striated regularity can help to bound the gradient of the velocity, we can prove the global well-posedness of the Boussinesq system with anisotropic thermal diffusion with initial vorticity being discontinuous across some smooth interface. In the case of an anisotropic horizontal viscosity we can study the propagation of the striated regularity for the smooth temperature patches problem.Comment: 36 page

    Isospin breaking, coupled-channel effects, and X(3872)

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    We re-investigate the possibility of X(3872) as a DDΛ‰βˆ—D\bar{D}^* molecule with JPC=1++J^{PC}=1^{++} within the framework of both the one-pion-exchange (OPE) model and the one-boson-exchange (OBE) model. After careful treatment of the S-D wave mixing, the mass difference between the neutral and charged D(Dβˆ—)D(D^*) mesons and the coupling of the D(Dβˆ—)D(D^*) pair to Dβˆ—DΛ‰βˆ—D^*\bar{D}^*, a loosely bound molecular state X(3872) emerges quite naturally with large isospin violation in its flavor wave function. For example, the isovector component is 26.24% if the binding energy is 0.30 MeV, where the isospin breaking effect is amplified by the tiny binding energy. After taking into account the phase space difference and assuming the 3Ο€3\pi and 2Ο€2\pi come from a virtual omega and rho meson respectively, we obtain the ratio of these two hidden-charm decay modes: B(X(3872)β†’Ο€+Ο€βˆ’Ο€0J/ψ)/B(X(3872)β†’Ο€+Ο€βˆ’J/ψ)=0.42\mathcal{B}(X(3872)\rightarrow \pi^+\pi^-\pi^0 J/\psi)/\mathcal{B}(X(3872)\rightarrow \pi^+\pi^- J/\psi)=0.42 for the binding energy being 0.3 MeV, which is consistent with the experimental value.Comment: published in Phys. Rev.

    Rain or Shine: Where is the Weather Effect?

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    Saunders (1993) and Hirshleifer and Shumway (2001) document the effect of weather on stock returns. The proposed explanation in both papers is that investor mood affects cognitive processes and trading decisions. In this paper, we use a database of individual investor accounts to examine the weather effects on traders. Our analysis of the trading activity in five major U.S. cities over a six-year period finds vistually no difference in individuals propensity to buy or sell equities on cloudy days as opposed to sunny days. If the association between cloud cover and stock returns documented for New York and other world cities is indeed caused by investor mood swings, our findings suggest that researchers should focus on the attitudes of market-makers, news providers or other agents physically located in the city hosting the exchange. NYSE spreads widen on cloudy days. When we control for this, the significance of the weather effect is dramatically reduced. We interpret this as evidence that the behavior of market-makers, rather than individual investors, may be responsible for the relation between returns and weather.

    Deuteron-like states composed of two doubly charmed baryons

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    We present a systematic investigation of the possible molecular states composed of a pair of doubly charmed baryons (ΞccΞcc\Xi_{cc}\Xi_{cc}) or one doubly charmed baryon and one doubly charmed antibaryon (ΞccΞžΛ‰cc)(\Xi_{cc}\bar{\Xi}_{cc}) within the framework of the one-boson-exchange-potential model. For the spin-triplet systems, we take into account the mixing between the 3S1{}^3S_1 and 3D1{}^3D_1 channels. For the baryon-baryon system ΞccΞcc\Xi_{cc}\Xi_{cc} with (R,I)=(3Λ‰,1/2)(R,I) = (\bar{3}, 1/2) and (3Λ‰,0)(\bar{3}, 0), where RR and II represent the group representation and the isospin of the system, respectively, there exist loosely bound molecular states. For the baryon-antibaryon system ΞccΞžΛ‰cc\Xi_{cc}\bar{\Xi}_{cc} with (R,I)=(8,1)(R,I) = (8, 1), (8,1/2)(8, 1/2) and (8,0)(8,0), there also exist deuteron-like molecules. The BccBΛ‰ccB_{cc}\bar{B}_{cc} molecular states may be produced at LHC. The proximity of their masses to the threshold of two doubly charmed baryons provides a clean clue to identify them.Comment: 18 pages, 8 figure

    Highlights of Supersymmetric Hypercharge Β±1\pm1 Triplets

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    The discovery of a standard model (SM)-like Higgs boson with a relatively heavy mass mhm_h and hints of di-photon excess has deep implication to supersymmetric standard models (SSMs). We consider the SSM extended with hypercharge Β±1\pm1 triplets, and investigate two scenarios of it: (A) Triplets significantly couple to the Higgs doublets, which can substantially raise mhm_h and simultaneously enhance the Higgs to di-photon rate via light chargino loops; (B) Oppositely, these couplings are quite weak and thus mhm_h can not be raised. But the doubly-charged Higgs bosons, owing to the gauge group structure, naturally interprets why there is an excess rather than a deficient of Higgs to di-photon rate. Additionally, the pseudo Dirac triplet fermion is an inelastic non-thermal dark matter candidate. Light doubly-charged particles, especially the doubly-charged Higgs boson around 100 GeV in scenario B, are predicted. We give a preliminary discussion on their search at the LHC.Comment: JHEP version. Typos fixed, comments, references and acknowledge adde

    Flavor Violating Transitions of Charged Leptons from a Seesaw Mechanism of Dimension Seven

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    A mechanism has been suggested recently to generate the neutrino mass out of a dimension-seven operator. This is expected to relieve the tension between the occurrence of a tiny neutrino mass and the observability of other physics effects beyond it. Such a mechanism would inevitably entail lepton flavor violating effects. We study in this work the radiative and purely leptonic transitions of the light charged leptons. In so doing we make a systematic analysis of the flavor structure by providing a convenient parametrization of the mass matrices in terms of independent physical parameters and diagonalizing them explicitly. We illustrate our numerical results by sampling over two CP phases and one Yukawa coupling which are the essential parameters in addition to the heavy lepton mass. We find that with the stringent constraints coming from the muon decays and the muon-electron conversion in nuclei taken into account the decays of the tau lepton are severely suppressed in the majority of parameter space. There exist, however, small regions in which some tau decays can reach a level that is about 2 orders of magnitude below their current bounds.Comment: v1: 25 pages, 8 figures; v2: proofread version for PRD. Included muon-electron conversion in nuclei at the referee's suggestion and added relevant refs accordingly; main conclusion not changed but bounds on tau lepton decays becoming more stringent; linguistic and editing corrections also mad

    Possible hadronic molecules composed of the doubly charmed baryon and nucleon

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    We perform a systematical investigation of the possible deuteron-like bound states with configuration ΞccN(NΛ‰)\Xi_{cc}N (\bar{N}), where N(NΛ‰)N(\bar{N}) denotes the nucleon (anti-nucleon), in the framework of the one-boson-exchange-potential model. In the spin-triplet sector we take into account both the 3S1{}^3S_1 and 3D1{}^3D_1 channels due to non-vanishing tensor force. There exist several candidates of the loosely bound molecular states for the ΞccN\Xi_{cc}N and ΞccNΛ‰\Xi_{cc}\bar{N} systems, which lie below the threshold of Ξ›cΞ›c\Lambda_c\Lambda_c or Ξ›cΞ›Λ‰c\Lambda_c{\bar\Lambda}_c. We also investigate the possible loosely bound states with configurations Ξ›cN(NΛ‰)\Lambda_cN(\bar{N}) and Ξ£cN(NΛ‰)\Sigma_cN(\bar{N}). These molecular candidates may be searched for at Belle II and LHC in the near future.Comment: 14 pages, 5 figure
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